If I moved into a house owned by my de facto who pays for everything and haven't slept together for 4 years, I work & occasionally buy food. Am I entitled to half his property in a property settlement?
There is no hard and fast rule. You may be eligible to apply for a property settlement order if you are in a de facto relationship for longer than 2 years. However, what your share of the "shared assets" is will depend on a number of factors, including:
Each partner's actual and relative contribution before and during the relationship
Any contribution made after separation
Relative earning capacity of each partner
Dependants and financial obligations
Future financial needs (e.g. health, age, available access to financial resources)
If your partner contributes more financially, contributed the house that you both currently live in and "pay for everything" as you say and you contribute financially for food, you will unlikely get half of the shared assets.